IMPACT OF AN ENVIRONMENTALLY-REALISTIC INTAKE OF CADMIUM ON CALCIUM, MAGNESIUM, AND PHOSPHATE-METABOLISM IN BANK VOLES, CLETHRIONOMYS-GLAREOLUS

Oral intake of cadmium can disrupt calcium metabolism in laboratory ro dents. If this occurs in free-living wild rodents, reproductive potent ial, growth, and survival could be adversely affected. This study inve stigated whether an environmentally-realistic intake of cadmium (1.5-1 .7 mg/kg BW/24h) by bank voles, Clethrionomys glareolus, affected upta ke and assimilation of calcium and also that of magnesium and phosphor us, two elements metabolized in close association with calcium. Minera l metabolism was monitored in bank voles fed four different diets; two diets were relatively low (0.12%) in calcium and contained either no cadmium (LC) or cadmium (LCCd), while the remainder were relatively hi gh (0.74%) in calcium and also contained either no cadmium (HC) or cad mium (HCCd). Dietary calcium levels were varied because calcium can af fect gut absorption of cadmium, and calcium levels in natural forage v ary with habitat soil type. Cadmium had a significant effect on voles' fed a low calcium diet. Animals given LCCd diet had significantly poo rer calcium net gut absorption efficiency than animals fed the corresp onding control (LC) diet and were in negative calcium balance, losing approximately 0.5-1% of body calcium reserves each day. In contrast, c alcium inputs matched total outputs in animals fed the LC diet. Cadmiu m had no effect on net gut absorption of magnesium and phosphorus, but renal reabsorption and subsequent assimilation of these elements was greater in animals fed the LCCd diet than in those given the LC diet. Cadmium had no clear effect on macroelement metabolism in bank voles f ed a diet relatively high in calcium. Net gut absorption and assimilat ion of calcium by voles fed the HCCd diet was reduced to the same exte nt as observed in animals fed the LCCd diet. However, because of their high dietary calcium intake, voles fed the HCCd diet maintained a pos itive calcium balance and there was no significant difference in calci um assimilation between animals fed the HCCd and HC diet. Cadmium had no effect on magnesium and phosphorus metabolism in voles fed high cal cium diets.